JP3830170B2 - Manufacturing method of liquid crystal device - Google Patents

Manufacturing method of liquid crystal device Download PDF

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JP3830170B2
JP3830170B2 JP53057399A JP53057399A JP3830170B2 JP 3830170 B2 JP3830170 B2 JP 3830170B2 JP 53057399 A JP53057399 A JP 53057399A JP 53057399 A JP53057399 A JP 53057399A JP 3830170 B2 JP3830170 B2 JP 3830170B2
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liquid crystal
voltage
image data
voltage value
manufacturing
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近藤　　真哉
鈴太郎 高橋
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Citizen Watch Co Ltd
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    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
    • G09G3/36—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source using liquid crystals
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
    • G09G3/36—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source using liquid crystals
    • G09G3/3611—Control of matrices with row and column drivers
    • G09G3/3622—Control of matrices with row and column drivers using a passive matrix
    • G09G3/3629—Control of matrices with row and column drivers using a passive matrix using liquid crystals having memory effects, e.g. ferroelectric liquid crystals
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2320/00—Control of display operating conditions
    • G09G2320/02—Improving the quality of display appearance
    • G09G2320/029—Improving the quality of display appearance by monitoring one or more pixels in the display panel, e.g. by monitoring a fixed reference pixel
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/006—Electronic inspection or testing of displays and display drivers, e.g. of LED or LCD displays
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
    • G09G3/36—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source using liquid crystals
    • G09G3/3611—Control of matrices with row and column drivers
    • G09G3/3696—Generation of voltages supplied to electrode drivers

Description

発明の属する技術分野
本発明は液晶装置の製造方法に関し、特にスメクティック液晶装置において、最適な駆動電圧値を自動的に求め、その電圧値で駆動するための液晶装置の製造方法に関する。
従来の技術
液晶パネルは軽薄短小でありながら、ＣＲＴと同等の表示品位を得ることができるため近年盛んに研究開発がなされている。最近ではテレビやコンピューターなどのモニターとして用いられるだけではなく、光シャッター等のいわゆる空間光変調素子としても用いられている。
液晶パネルに用いられている液晶材料において、液晶分子の状態がスイッチングする閾値電圧は温度依存性を有している。また、液晶パネルは見る角度によって表示品位が異なる視角依存性を有する。そのため、従来の液晶装置では動作している状態で最適な表示が行われるように液晶に印加される電圧を調整するための装置が設けられており、実際に液晶の画面を見ながら最適表示となるように電圧の調整を行っていた。
発明の開示
しかし液晶パネルを空間光変調素子として用いる場合は装置内部に組み込まれるため、直接人間の目で液晶パネルの表示状態を確認することが出来ない。そこで本発明は人間の目で直接液晶パネルの表示状態を確認できない場合に、液晶パネルの表示状態が最も最適な状態（即ち、最もコントラストの高い状態）とするために必要な駆動電圧の値（以下、「最適駆動電圧値」と記す）を自動的に求める液晶装置の製造方法を提供することを目的する。
本発明による液晶装置の製造方法は、表示装置または２次元的な光信号の光量調節を非常に高速に行う空間光変調素子等に用いられる。本発明による液晶装置を空間光変調素子として用いた場合、液晶パネルは入力してきた２次元の光信号を所定の状態の出力光にする、光に対するシャッターの役目を果たす。
本発明液晶装置の製造方法は、特に強誘電性液晶や反強誘電性液晶などのスメクティック液晶を用いた液晶装置を対象としている。
上記目的を達成するため、本発明の製造方法が適用される液晶装置は以下の構成を有している。
上記液晶装置は、一対の基板間にスメクティック液晶を挟持してなる液晶パネルと、液晶パネルに表示された画像を取り込むための表示取り込み装置と、取り込まれた画像データを記憶する取り込みメモリと、参照画像データを記憶する参照メモリと、前記取り込みメモリ及び参照メモリのそれぞれに記憶されているデータを比較する表示差回路と、前記液晶パネルへの印加電圧値を可変するための電圧値可変回路と、最適電圧設定手段とを備えている。
また、本発明が適用される液晶装置は、複数の信号電極と走査電極とを有する１対の基板間にスメクティック液晶を挟持してなる液晶パネルを有している。そして、信号電極に印加される信号電圧と走査電極に印加される走査電圧とをそれぞれ変化させ、信号電圧と走査電圧の各組み合わせにおける液晶パネルの表示を前記表示取り込み装置で取り込む。取り込まれた画像データを取り込みメモリに記憶し、前記取り込まれた画像データと前記参照画像データを比較する。そして、２つのデータが一致する信号電圧と走査電圧の各組み合わせを、信号電圧及び走査電圧をそれぞれのＸ軸及びＹ軸とした座標にプロットする。プロットされた点によって描かれる領域の重心の座標に相当する信号電圧値及び走査電圧値をそれぞれ最適駆動電圧値として設定する。
また、液晶装置の適応可能な最高温度及び最低温度において、同じ動作を行い、プロットされた領域を求める。そして、最高温度においてプロットされた点によって描かれる領域と最低温度においてプロットされた点によって描かれる領域と重なる領域の重心の座標に相当する信号電圧値及び走査電圧値をそれぞれ最適駆動電圧値として設定する。
発明の効果
本発明の液晶表示装置を用いることにより液晶パネルの表示状態を直接目視観察できない場合でも最適駆動電圧を設定することができる。また、この方法で求めた最適駆動電圧を用いることにより、温度等の変動で液晶の閾値電圧等が多少変化した場合でも駆動電圧を調整することなく最適な表示を行うことが出来る。
【図面の簡単な説明】
図１は、強誘電性液晶における液晶分子の安定状態を示した図である。
図２は、強誘電性液晶セルと偏光板の構成図である。
図３は、強誘電性液晶素子の印加電圧に対する光透過率の変化を示す図である。
図４は、反強誘電性液晶セルと偏光板の構成図である。
図５は、反強誘電性液晶素子の印加電圧に対する光透過率の変化を示す図である。
図６は、本発明で用いた液晶パネルの構成図である。
図７は、本発明で用いた液晶パネルの電極構成の例を示す図である。
図８は、最適駆動電圧設定回路を組み込んだ本発明が適用される液晶装置のブロック図である。
図９は、本発明で用いたサンプル表示を示した図である。
図１０は、本発明で用いた液晶パネルの駆動可能な電圧値の領域を示した図である。
図１１は、本発明で用いた液晶パネルの、35℃と45℃において駆動可能な電圧値の領域を示した図である。
図１２は、最適駆動電圧設定回路を組み込んだ本発明が適用される液晶装置の別の実施形態のブロック図である。
発明の詳細な説明
図１は、強誘電性液晶の安定状態を示した図である。強誘電性液晶は図１に示すように２つの安定状態を持ち、印加電圧の極性によって第１又は第２の安定状態にスイッチングする。
図２は強誘電性液晶を液晶素子として用いる場合の偏光板の配置を示す図である。クロスニコルに合わせた偏光板１ａ、１ｂの間に、偏光板１ａの偏光軸ａと偏光板１ｂの偏光軸ｂのどちらか一方と、液晶分子の第１の安定状態もしくは第２の安定状態のときの分子長軸方向のどちらかとがほぼ平行になるように液晶セル２を置く。
このような液晶セルに電圧を印加したとき、それに対する透過率変化をプロットしてグラフにすると図３のようなループを描く。負の電圧を印加し、光透過率が変化し始める電圧値をＶ１、光透過率の変化が飽和する電圧値をＶ２、これより逆極性の電圧を印加して、光透過率が減少し始める電圧値をＶ３、光透過率変化が飽和する電圧値をＶ４とする。図３に示されているように、前記印加された電圧値が強誘電性液晶分子の閾値以上である場合に第１の安定状態が得られる。また、強誘電性液晶分子の閾値以上である逆極性の電圧が印加された場合は、第２の安定状態が選択される。
図２のように偏光板を設置すると、第１の安定状態で黒状態（非透過状態）、第２の安定状態で白状態（透過状態）とすることができる。なお、偏光板の設置を変えることにより、第１の安定状態で白状態（透過状態）、第２の安定状態で黒状態（非透過状態）とすることができる。
図４は反強誘電性液晶を液晶素子として用いる場合の偏光板の配置を示す図である。クロスニコルに合わせた偏光板１ａ、１ｂの間に、偏光板１ａの偏光軸ａと偏光板１ｂの偏光軸ｂのどちらかと電圧無印加時に於ける平均的な分子の長軸方向Ｘがほぼ平行になるように液晶セル２を置く。そして、電圧無印加時に黒状態となり、電圧印加時には白状態となるように液晶セルを設定する。
このような液晶セルに電圧を印加したとき、それに対する透過率変化をプロットしてグラフにすると図５のようなループを描く。電圧を印加し増加させたとき光透過率が変化し始める電圧値をＶ１、光透過率の変化が飽和する電圧値をＶ２、逆に電圧値を減少させたとき光透過率が減少し始める電圧値をＶ５、また逆極性の電圧を印加し、その絶対値を増加させたときに光透過率が変化し始める電圧値をＶ３、光透過率変化が飽和する電圧値をＶ４、逆に電圧の絶対値を減少させたとき光透過率が変化し始める電圧値をＶ６とする。図５に示されているように、前記印加された電圧値が反強誘電性液晶分子の閾値以上である場合に第１の強誘電性状態が選択される。また、反強誘電性液晶分子の閾値以上である逆極性の電圧が印加された場合は、第２の強誘電性状態が選択される。これらの強誘電性状態において、電圧値がある閾値より低くなった場合には反強誘電性状態が選択される。
図６に示す本発明で用いた液晶パネルは、約1.7μの厚さの強誘電性液晶層又は反強誘電性液晶層22を持つ一対のガラス基板23ａ，23ｂから構成されている。ガラス基板の対向面には電極24ａ，24ｂが形成されており、その上に無機配向膜25ａ，25ｂが蒸着されている。さらに１方のガラス基板の外側に偏光板21ａが設置されており、他方のガラス基板の外側には偏光板21ａの偏光軸と90°異なるようにして偏光板21ｂが設置されている。
本発明に用いられている液晶装置は、光制御装置内に設置してある場合には液晶パネルの表示状態を外部から目視で観察することが出来ない。そこで本発明における液晶装置には、液晶パネルの表示状態が最適になるような最適駆動電圧値を自動的に設定するための装置が組み込まれている。なお、ここで言う表示とは液晶を表示装置として用いた場合の画像の表示、及び液晶をシャッター等に用いた場合の透過光量の両者を意味するものとする。
図７はマトリックス駆動を行う場合の液晶パネルの電極構成の例を示す。液晶の駆動を行うため走査電極（Y1〜Yn）と信号電極（X1〜Xn）に電圧波形を印加する。液晶の状態は、それぞれの電極に印加される電圧波形の電圧値に依存している。
図８は最適駆動電圧設定回路を組み込んだ本発明が適用される液晶装置のブロック図である。液晶パネル１５には信号電極１６と走査電極１７が設けられている。そして、これらの電極に電圧値可変回路１８から駆動電圧波形が印加され、液晶パネルに駆動電圧波形に応じた表示が行われる。表示取り込み装置２０はＣＣＤ素子１３とレンズ１４を有し、液晶パネルの最適表示画像（後述）を取り込んで参照メモリに記憶させる。表示取り込み装置２０は、また液晶パネルのサンプル表示（後述）を取り込んで取り込みメモリ１１に記憶させる。そして、参照メモリ１０のデータと取り込みメモリ１１のデータが一致しているかどうかが表示差回路１２で判定され、その結果に応じて最適電圧設定用ＣＰＵ１９は電圧値可変回路１８を制御する。
次に、図８に示された最適駆動電圧設定回路を組み込んだ本発明の液晶装置の動作を説明する。
図９は、白と黒のパターンが交互に並んだサンプル表示２１を示した図である。液晶パネル１５を、例えば光制御装置に組み込む前に、サンプル表示２１と同じパターンを表示させる。この時、目視観察しながら液晶パネル１５の信号電極１６と走査電極１７に印加される電圧を調整し、最適な表示の画像（以下、「参照画像」と記す）を得る。そして、この画像を表示取り込み装置２０によって取り込み、取り込まれた参照画像データは参照メモリ１０に記憶される。
次に、液晶パネルを光制御装置に組み込んだ後、最適駆動電圧値を自動的に求める動作について説明する。液晶パネルを光制御装置に組み込んだ後、図９のサンプル表示２１と同じパターンを表示する。そして、表示された画像を表示取り込み装置２０によって取り込み、取り込まれた画像は取り込みメモリ１１に記憶される。次に、参照メモリ１０に記憶されている最適な表示の画像の参照データと、取り込みメモリ１１に記憶されている画像データが一致しているかどうかを表示差回路１２で判定する。
より具体的に本発明の液晶装置の製造方法を図１０を参照して説明する。まず、信号電圧と走査電圧をそれぞれ１Ｖに設定する。次に、その時の液晶パネル１５の表示を表示取り込み装置２０で取り込み、取り込まれた画像データを取り込みメモリ１１に記憶する。次に、参照メモリ１０に記憶されている参照画像データと取り込みメモリ１１に記憶された前記液晶パネルの画像データが一致するどうかが表示差回路１２で判定する。そして、２つのデータが一致したとき、図１０に示すグラフの横軸の信号電圧１Ｖと縦軸の走査電圧１Ｖの線が交差する点にプロットする。
次に、信号電圧を１Ｖに保持し、走査電圧を１．５Ｖに上げる。そして、先に述べたと同じようにその時の液晶パネル１５の表示を表示取り込み装置２０で取り込み、取り込まれた画像データを取り込みメモリ１１に記憶する。次に、参照メモリ１０に記憶されている参照画像データと取り込みメモリ１１に記憶された前記液晶パネルの画像データが一致するどうかが表示差回路１２で判定する。そして、２つのデータが一致したとき、図１０に示すグラフの横軸の信号電圧１Ｖと縦軸の走査電圧１．５Ｖの線が交差する点にプロットする。２つのデータが一致しないときはプロットされない。上記動作を走査電圧が２０Ｖになるまで０．５Ｖ間隔で増加して行う。
次に、信号電圧を１．５Ｖに設定し、走査電圧を１Ｖから０．５Ｖ間隔で増加し、上記と同じ動作を行う。なお、上記動作では信号電圧及び走査電圧は１Ｖの値から開始され、０．５Ｖ間隔で増加している。しかし、これらの値は適宜変更してもよい。
上記動作を行って、２つのデータが一致したときの走査電圧と信号電圧が交差した点をプロットした結果が図１０に示されている。図１０に示されているように、プロットされた領域は三角形となる（以下、この三角形の領域を「駆動可能領域」と記す）。そして、「駆動可能領域」の重心の位置を求め、重心の位置に対応する信号電圧と走査電圧を「最適駆動電圧値」として用いる。このように重心の位置に対応する信号電圧及び走査側電圧を最適駆動電圧値として用いることにより、走査電圧や信号電圧が多少変動しても、上記三角領域を外れずに最適駆動をすることができる。この結果、温度の変化等で液晶の駆動電圧値が多少変動した場合でも最適な表示をすることが可能な駆動電圧として使用することができる。
なお、上記最適駆動電圧値を求める動作の制御は、図８の最適電圧設定用ＣＰＵ１９によって行われる。
また、液晶装置を使用する環境の温度変化が大きい場合には、使用する温度の最低温度と最高温度でそれぞれ駆動可能領域を求め、両方の駆動可能領域が重なりあった三角領域の重心を求め、重心の位置に対応する信号側及び走査側の電圧値を最適駆動電圧値として用いる。
図１１は上記のようにして求めた三角領域を示したものである。使用する環境の最低温度、例えば３５℃において、上記と同様の方法で三角領域（Ａ）を求める。また、使用する環境の最高温度、例えば４５℃において、上記と同様の方法で三角領域（Ｂ）を求める。そして、三角領域（Ａ）と（Ｂ）が重なった三角領域（Ｃ）の重心を求め、重心の位置に対応する信号電圧と走査電圧を「最適駆動電圧値」として用いる。このように求めた「最適駆動電圧値」を用いることにより、３５℃から４５℃までの温度変化に対して、駆動電圧値の補正を行うことなく、安定した表示を行うことができる。
本実施形態においては、ＣＣＤ素子１３とレンズ１４からなる表示取り込み装置２０によって画像データを直接取り込む場合を説明した。しかし、別の実施形態として、図１２に示すように、透過光量を集光するためのレンズ74と集光した光を受けて光量を測定するための透過光量測定装置７３（例えば、フォトダイオードとアンプから構成）で構成することができる。この構成では、画像を映し出した液晶パネル全域からの透過光量を取り込む。透過光量測定装置７３は、最適表示画像である参照画像の透過光量を取り込んで透過光量のデータを参照メモリ１０に記憶させる。透過光量測定装置７３は、また液晶パネルのサンプル表示の透過光量を取り込んで取り込みメモリ１１に記憶させる。そして、参照メモリ１０のデータと取り込みメモリ１１のデータが一致しているかどうかが表示差回路１２で判定され、その結果に応じて最適電圧設定用ＣＰＵ１９は電圧値可変回路１８を制御する。これにより、図８に示されたものと同様の効果を得ることができ、かつＣＣＤ素子を用いる場合と比べて構成を簡単にするとができる。
図８及び図１２に示した本発明の実施形態においては、パッシブマトリクスを用いた液晶装置を例に説明した。しかし、アクティブマトリクスを用いた液晶装置にも本発明を適用できることは勿論である。TECHNICAL FIELD The present invention Field of the Invention relates to a method of manufacturing a liquid crystal device, particularly in smectic liquid crystal device, automatically determine the optimum drive voltage values, a method for manufacturing a liquid crystal device for driving at the voltage value.
Conventional technology liquid crystal panels are light, thin, and small, and can obtain display quality equivalent to that of CRTs, and thus have been actively researched and developed in recent years. Recently, it is used not only as a monitor for televisions and computers, but also as a so-called spatial light modulation element such as an optical shutter.
In a liquid crystal material used for a liquid crystal panel, a threshold voltage at which the state of liquid crystal molecules switches has temperature dependency. Further, the liquid crystal panel has a viewing angle dependency in which display quality varies depending on the viewing angle. For this reason, a conventional liquid crystal device is provided with a device for adjusting the voltage applied to the liquid crystal so that an optimum display is performed in an operating state. The voltage was adjusted so that
DISCLOSURE OF THE INVENTION However, when the liquid crystal panel is used as a spatial light modulation element, it is incorporated in the device, and thus the display state of the liquid crystal panel cannot be confirmed directly by human eyes. Therefore, according to the present invention, when the display state of the liquid crystal panel cannot be confirmed directly by human eyes, the value of the driving voltage necessary for making the display state of the liquid crystal panel the most optimal state (that is, the state with the highest contrast) ( Hereinafter, an object of the present invention is to provide a method of manufacturing a liquid crystal device that automatically obtains “optimum driving voltage value”.
The method for manufacturing a liquid crystal device according to the present invention is used for a display device or a spatial light modulation element that adjusts the amount of light of a two-dimensional optical signal at a very high speed. When using a liquid crystal device according to the present invention as a spatial light modulator, a liquid crystal panel is a two-dimensional optical signals that have entered in the output light of the predetermined state, it acts as a shutter against light.
The manufacturing method of the liquid crystal device of the present invention is particularly intended for a liquid crystal device using a smectic liquid crystal such as a ferroelectric liquid crystal or an antiferroelectric liquid crystal.
In order to achieve the above object, a liquid crystal device to which the manufacturing method of the present invention is applied has the following configuration.
The liquid crystal device includes a liquid crystal panel having a smectic liquid crystal sandwiched between a pair of substrates, a display capturing device for capturing an image displayed on the liquid crystal panel, a capturing memory for storing captured image data, and a reference A reference memory for storing image data, a display difference circuit for comparing data stored in each of the capture memory and the reference memory, a voltage value variable circuit for varying a voltage value applied to the liquid crystal panel, And an optimum voltage setting means.
A liquid crystal device to which the present invention is applied has a liquid crystal panel in which a smectic liquid crystal is sandwiched between a pair of substrates having a plurality of signal electrodes and scanning electrodes. Then, the signal voltage applied to the signal electrode and the scanning voltage applied to the scanning electrode are respectively changed, and the display on the liquid crystal panel in each combination of the signal voltage and the scanning voltage is captured by the display capturing device. The captured image data is stored in a capture memory, and the captured image data is compared with the reference image data. Then, each combination of the signal voltage and the scanning voltage in which the two data coincide with each other is plotted on the coordinates with the signal voltage and the scanning voltage as the X axis and the Y axis, respectively. A signal voltage value and a scanning voltage value corresponding to the coordinates of the center of gravity of the region drawn by the plotted points are set as optimum drive voltage values.
Further, the same operation is performed at the maximum temperature and the minimum temperature applicable to the liquid crystal device, and the plotted area is obtained. Then, the signal voltage value and the scanning voltage value corresponding to the coordinates of the center of gravity of the region drawn by the point plotted at the highest temperature and the region drawn by the point plotted at the lowest temperature are set as the optimum driving voltage values, respectively. To do.
EFFECT OF THE INVENTION By using the liquid crystal display device of the present invention, the optimum driving voltage can be set even when the display state of the liquid crystal panel cannot be directly visually observed. Further, by using the optimum drive voltage obtained by this method, even when the threshold voltage of the liquid crystal slightly changes due to a change in temperature or the like, an optimum display can be performed without adjusting the drive voltage.
[Brief description of the drawings]
FIG. 1 is a diagram showing a stable state of liquid crystal molecules in a ferroelectric liquid crystal.
FIG. 2 is a configuration diagram of a ferroelectric liquid crystal cell and a polarizing plate.
FIG. 3 is a diagram showing a change in light transmittance with respect to an applied voltage of the ferroelectric liquid crystal element.
FIG. 4 is a configuration diagram of an antiferroelectric liquid crystal cell and a polarizing plate.
FIG. 5 is a diagram showing a change in light transmittance with respect to an applied voltage of the antiferroelectric liquid crystal element.
FIG. 6 is a configuration diagram of the liquid crystal panel used in the present invention.
FIG. 7 is a diagram showing an example of the electrode configuration of the liquid crystal panel used in the present invention.
FIG. 8 is a block diagram of a liquid crystal device to which the present invention incorporating the optimum drive voltage setting circuit is applied .
FIG. 9 is a diagram showing a sample display used in the present invention.
FIG. 10 is a diagram showing a voltage value region in which the liquid crystal panel used in the present invention can be driven.
FIG. 11 is a diagram showing voltage value regions that can be driven at 35 ° C. and 45 ° C. of the liquid crystal panel used in the present invention.
FIG. 12 is a block diagram of another embodiment of a liquid crystal device to which the present invention is applied , incorporating an optimum drive voltage setting circuit.
DETAILED DESCRIPTION OF THE INVENTION FIG. 1 is a diagram showing a stable state of a ferroelectric liquid crystal. The ferroelectric liquid crystal has two stable states as shown in FIG. 1, and switches to the first or second stable state depending on the polarity of the applied voltage.
FIG. 2 is a diagram showing the arrangement of polarizing plates when a ferroelectric liquid crystal is used as a liquid crystal element. Between the polarizing plates 1a and 1b matched to crossed Nicols, either the polarizing axis a of the polarizing plate 1a or the polarizing axis b of the polarizing plate 1b, and the first stable state or the second stable state of the liquid crystal molecules The liquid crystal cell 2 is placed so that either one of the molecular long axes is almost parallel.
When a voltage is applied to such a liquid crystal cell, the change in transmittance with respect to the voltage is plotted to form a graph as shown in FIG. When a negative voltage is applied, the voltage value at which the light transmittance starts to change is V1, the voltage value at which the light transmittance change is saturated is V2, and a voltage having a polarity opposite thereto is applied, so that the light transmittance starts to decrease. The voltage value is V3, and the voltage value at which the light transmittance change is saturated is V4. As shown in FIG. 3, the first stable state is obtained when the applied voltage value is greater than or equal to the threshold value of the ferroelectric liquid crystal molecules. In addition, when a reverse polarity voltage that is equal to or higher than the threshold value of the ferroelectric liquid crystal molecules is applied, the second stable state is selected.
When a polarizing plate is installed as shown in FIG. 2, the first stable state can be a black state (non-transmission state), and the second stable state can be a white state (transmission state). In addition, by changing the installation of the polarizing plate, the first stable state can be in a white state (transmission state), and the second stable state can be in a black state (non-transmission state).
FIG. 4 is a diagram showing the arrangement of polarizing plates when antiferroelectric liquid crystal is used as a liquid crystal element. Between the polarizing plates 1a and 1b matched to crossed Nicols, either the polarizing axis a of the polarizing plate 1a or the polarizing axis b of the polarizing plate 1b is substantially parallel to the major axis direction X of the average molecule when no voltage is applied. The liquid crystal cell 2 is placed so that Then, the liquid crystal cell is set so as to be in a black state when no voltage is applied and in a white state when a voltage is applied.
When a voltage is applied to such a liquid crystal cell, the change in transmittance with respect to the voltage is plotted to form a graph as shown in FIG. When the voltage is applied and increased, the voltage value at which the light transmittance starts to change is V1, the voltage value at which the light transmittance change is saturated is V2, and conversely, when the voltage value is decreased, the light transmittance starts to decrease. When V5 is applied and a reverse polarity voltage is applied and the absolute value is increased, the voltage value at which the light transmittance starts to change is V3, the voltage value at which the light transmittance change is saturated is V4, and the voltage A voltage value at which the light transmittance starts to change when the absolute value is decreased is defined as V6. As shown in FIG. 5, the first ferroelectric state is selected when the applied voltage value is greater than or equal to the threshold value of the antiferroelectric liquid crystal molecules. In addition, when a voltage having a reverse polarity equal to or higher than the threshold value of the antiferroelectric liquid crystal molecules is applied, the second ferroelectric state is selected. In these ferroelectric states, when the voltage value becomes lower than a certain threshold value, the antiferroelectric state is selected.
The liquid crystal panel used in the present invention shown in FIG. 6 is composed of a pair of glass substrates 23a and 23b having a ferroelectric liquid crystal layer or an antiferroelectric liquid crystal layer 22 having a thickness of about 1.7 μm. Electrodes 24a and 24b are formed on opposite surfaces of the glass substrate, and inorganic alignment films 25a and 25b are deposited thereon. Further, a polarizing plate 21a is provided outside one glass substrate, and a polarizing plate 21b is provided outside the other glass substrate so as to be 90 ° different from the polarization axis of the polarizing plate 21a.
When the liquid crystal device used in the present invention is installed in the light control device, the display state of the liquid crystal panel cannot be visually observed from the outside. Therefore, the liquid crystal device according to the present invention incorporates a device for automatically setting an optimum driving voltage value that optimizes the display state of the liquid crystal panel. In addition, the display said here shall mean both the display of the image when a liquid crystal is used as a display apparatus, and the transmitted light amount when a liquid crystal is used for a shutter etc.
FIG. 7 shows an example of the electrode configuration of the liquid crystal panel when performing matrix driving. In order to drive the liquid crystal, a voltage waveform is applied to the scan electrodes (Y1 to Yn) and the signal electrodes (X1 to Xn). The state of the liquid crystal depends on the voltage value of the voltage waveform applied to each electrode.
FIG. 8 is a block diagram of a liquid crystal device to which the present invention is incorporated, incorporating an optimum drive voltage setting circuit. The liquid crystal panel 15 is provided with signal electrodes 16 and scanning electrodes 17. Then, a drive voltage waveform is applied to these electrodes from the voltage value variable circuit 18, and a display corresponding to the drive voltage waveform is performed on the liquid crystal panel. The display capturing device 20 includes a CCD element 13 and a lens 14 and captures an optimal display image (described later) of the liquid crystal panel and stores it in a reference memory. The display capture device 20 also captures a sample display (described later) of the liquid crystal panel and stores it in the capture memory 11. The display difference circuit 12 determines whether or not the data in the reference memory 10 and the data in the capture memory 11 match, and the optimum voltage setting CPU 19 controls the voltage value variable circuit 18 according to the result.
Next, the operation of the liquid crystal device of the present invention incorporating the optimum drive voltage setting circuit shown in FIG. 8 will be described.
FIG. 9 is a diagram showing a sample display 21 in which white and black patterns are alternately arranged. For example, the same pattern as the sample display 21 is displayed before the liquid crystal panel 15 is incorporated in the light control device. At this time, the voltage applied to the signal electrode 16 and the scanning electrode 17 of the liquid crystal panel 15 is adjusted while visually observing to obtain an optimal display image (hereinafter referred to as “reference image”). The image is captured by the display capturing device 20, and the captured reference image data is stored in the reference memory 10.
Next, an operation for automatically obtaining the optimum drive voltage value after the liquid crystal panel is incorporated in the light control device will be described. After the liquid crystal panel is incorporated in the light control device, the same pattern as the sample display 21 in FIG. 9 is displayed. Then, the displayed image is captured by the display capture device 20, and the captured image is stored in the capture memory 11. Next, the display difference circuit 12 determines whether or not the reference data of the optimally displayed image stored in the reference memory 10 matches the image data stored in the capture memory 11.
More specifically, the manufacturing method of the liquid crystal device of the present invention will be described with reference to FIG. First, the signal voltage and the scanning voltage are each set to 1V. Next, the display on the liquid crystal panel 15 at that time is captured by the display capture device 20, and the captured image data is stored in the capture memory 11. Next, the display difference circuit 12 determines whether the reference image data stored in the reference memory 10 and the image data of the liquid crystal panel stored in the capture memory 11 match. When the two data coincide with each other, the graph is plotted at the point where the line of the signal voltage 1V on the horizontal axis and the scanning voltage 1V on the vertical axis intersects.
Next, the signal voltage is held at 1V and the scanning voltage is raised to 1.5V. Then, the display on the liquid crystal panel 15 at that time is captured by the display capturing device 20 as described above, and the captured image data is stored in the capturing memory 11. Next, the display difference circuit 12 determines whether the reference image data stored in the reference memory 10 and the image data of the liquid crystal panel stored in the capture memory 11 match. When the two data coincide with each other, the graph is plotted at the point where the line of the signal voltage 1V on the horizontal axis and the scanning voltage 1.5V on the vertical axis intersects. When the two data do not match, it is not plotted. The above operation is performed at 0.5V intervals until the scanning voltage reaches 20V.
Next, the signal voltage is set to 1.5 V, the scanning voltage is increased from 1 V to 0.5 V, and the same operation as described above is performed. In the above operation, the signal voltage and the scanning voltage start from a value of 1V and increase at intervals of 0.5V. However, these values may be changed as appropriate.
FIG. 10 shows the result of plotting the points where the scanning voltage and the signal voltage intersect when the above operation is performed and the two data match. As shown in FIG. 10, the plotted region is a triangle (hereinafter, this triangular region is referred to as a “driveable region”). Then, the position of the center of gravity of the “driveable region” is obtained, and the signal voltage and the scanning voltage corresponding to the position of the center of gravity are used as the “optimum driving voltage value”. Thus, by using the signal voltage corresponding to the position of the center of gravity and the scanning side voltage as the optimum driving voltage value, even if the scanning voltage and the signal voltage fluctuate somewhat, the optimum driving can be performed without departing from the triangular area. it can. As a result, even when the driving voltage value of the liquid crystal slightly fluctuates due to a change in temperature or the like, it can be used as a driving voltage capable of optimal display.
The operation for obtaining the optimum drive voltage value is controlled by the optimum voltage setting CPU 19 shown in FIG.
Also, when the temperature change in the environment where the liquid crystal device is used is large, obtain the driveable area at the lowest temperature and the highest temperature of use, respectively, find the center of gravity of the triangular area where both driveable areas overlap, The voltage value on the signal side and the scanning side corresponding to the position of the center of gravity is used as the optimum drive voltage value.
FIG. 11 shows the triangular area obtained as described above. The triangular area (A) is obtained by the same method as described above at the minimum temperature of the environment to be used, for example, 35 ° C. Further, the triangular region (B) is obtained by the same method as described above at the maximum temperature of the environment to be used, for example, 45 ° C. Then, the center of gravity of the triangular area (C) where the triangular areas (A) and (B) overlap is obtained, and the signal voltage and the scanning voltage corresponding to the position of the center of gravity are used as the “optimum driving voltage value”. By using the “optimum driving voltage value” thus obtained, stable display can be performed without correcting the driving voltage value for a temperature change from 35 ° C. to 45 ° C.
In the present embodiment, a case has been described in which image data is directly captured by the display capturing device 20 including the CCD element 13 and the lens 14. However, as another embodiment, as shown in FIG. 12, a lens 74 for condensing the transmitted light amount and a transmitted light amount measuring device 73 for receiving the collected light and measuring the light amount (for example, a photodiode) It can be composed of an amplifier). In this configuration, the amount of transmitted light from the entire liquid crystal panel on which an image is projected is captured. The transmitted light amount measuring device 73 captures the transmitted light amount of the reference image that is the optimum display image and stores the transmitted light amount data in the reference memory 10. The transmitted light amount measuring device 73 takes in the transmitted light amount of the sample display of the liquid crystal panel and stores it in the memory 11. The display difference circuit 12 determines whether or not the data in the reference memory 10 and the data in the capture memory 11 match, and the optimum voltage setting CPU 19 controls the voltage value variable circuit 18 according to the result. Thus, the same effect as that shown in FIG. 8 can be obtained, and the configuration can be simplified as compared with the case where a CCD element is used.
In the embodiment of the present invention shown in FIGS. 8 and 12, the liquid crystal device using the passive matrix has been described as an example. However, the present invention can of course be applied to a liquid crystal device using an active matrix.

Claims (9)

一対の基板間に液晶を挟持してなる液晶パネルの走査電極と信号電極とのそれぞれに任意の電圧を印加して、画像データを表示するステップと、
前記画像データの表示を表示取り込み装置で測定し、測定された前記画像データを取り込みメモリに記憶するステップと、
前記取り込みメモリに記憶された前記画像データと、参照メモリに記憶された参照画像データとを表示差回路にて比較するステップと、
前記画像データと前記参照画像データとが一致したときには、前記任意の電圧を記憶するステップと、
電圧値可変回路により前記液晶パネルに印加される前記任意の電圧を可変して、複数の記憶された前記任意の電圧を得るステップと、
前記複数の記憶された前記任意の電圧により、駆動可能領域を求めるステップと、
前記駆動可能領域から最適駆動電圧値を決定するステップと、
前記最適駆動電圧値を前記液晶パネルの駆動電圧値に設定するステップを有することを特徴とする液晶装置の製造方法。Applying an arbitrary voltage to each of a scanning electrode and a signal electrode of a liquid crystal panel having a liquid crystal sandwiched between a pair of substrates to display image data;
Measuring the display of the image data with a display capture device, and storing the measured image data in a memory;
Comparing the image data stored in the capture memory with reference image data stored in a reference memory by a display difference circuit;
Storing the arbitrary voltage when the image data matches the reference image data;
Varying the arbitrary voltage applied to the liquid crystal panel by a voltage value variable circuit to obtain a plurality of stored arbitrary voltages;
Obtaining a drivable region from the plurality of stored arbitrary voltages;
Determining an optimum drive voltage value from the drivable region;
A method of manufacturing a liquid crystal device comprising the step of setting the optimum drive voltage value to a drive voltage value of the liquid crystal panel. 前記走査電極と前記信号電極とのそれぞれに印加される前記任意の電圧は、それぞれ走査電圧と信号電圧であり、前記画像データと前記参照画像データとが一致したときには、前記走査電圧と前記信号電圧とを、Ｘ軸及びＹ軸とした座標にプロットして記憶することを特徴とする、請求項１に記載の液晶装置の製造方法。 The arbitrary voltages applied to the scan electrode and the signal electrode are a scan voltage and a signal voltage, respectively, and when the image data and the reference image data match, the scan voltage and the signal voltage The method of manufacturing a liquid crystal device according to claim 1, wherein: is plotted and stored in coordinates with the X-axis and the Y-axis. 前記座標にプロットされた領域が前記駆動可能領域であることを特徴とする請求項２に記載の液晶装置の製造方法。 3. The method of manufacturing a liquid crystal device according to claim 2 , wherein the area plotted on the coordinates is the drivable area. 前記駆動可能領域の重心の位置に対応する電圧値が前記最適駆動電圧値であることを特徴とする請求項１に記載の液晶装置の製造方法。2. The method of manufacturing a liquid crystal device according to claim 1, wherein a voltage value corresponding to a position of the center of gravity of the drivable region is the optimum driving voltage value. 前記液晶装置の適応可能な最高温度及び最低温度において、それぞれの温度にて前記駆動可能領域を求めるステップと、
前記最高温度における前記駆動可能領域と前記最低温度における前記駆動可能領域とが重なる領域を求めるステップと、
前記重なる領域より前記最適駆動電圧値を決定するステップを有することを特徴とする請求項１に記載の液晶装置の製造方法。Obtaining the drivable region at the respective maximum temperature and minimum temperature applicable to the liquid crystal device; and
Obtaining a region where the drivable region at the highest temperature and the drivable region at the lowest temperature overlap;
The method for manufacturing a liquid crystal device according to claim 1, further comprising a step of determining the optimum driving voltage value from the overlapping region. 前記重なる領域の重心の位置に対応する電圧値が前記最適駆動電圧値であることを特徴とする請求項５に記載の液晶装置の製造方法。6. The method of manufacturing a liquid crystal device according to claim 5 , wherein the voltage value corresponding to the position of the center of gravity of the overlapping region is the optimum driving voltage value. 前記表示取り込み装置はCCD素子を備えることを特徴とする請求項１に記載の液晶装置の製造方法。The method of manufacturing a liquid crystal device according to claim 1, wherein the display capturing device includes a CCD element. 前記表示取り込み装置は透過光量測定装置を備え、前記画像データおよび前記参照画像データは前記液晶パネルの全域による透過光量であることを特徴とする請求項１に記載の液晶装置の製造方法。The method of manufacturing a liquid crystal device according to claim 1, wherein the display capturing device includes a transmitted light amount measurement device, and the image data and the reference image data are transmitted light amounts over the entire area of the liquid crystal panel. 前記液晶はスメクティック液晶であることを特徴とする請求項１から８のいずれか１項に記載の液晶装置の製造方法。Method of manufacturing a liquid crystal device according to any one of claims 1 to 8, characterized in that said liquid crystal is a smectic liquid crystal.
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